1. Field of the Invention
This invention relates to a knee joint endoprosthesis system.
2. Prior Art
Knee joint endoprostheses are used to restore the knee-joint function after the natural knee joint is injured due to wear or damage to the bone, e.g., due to a tumor.
Knee joint endoprosthesis systems are already known from German Patent 198 16 984 A1, German Patent 197 08 375 A1, German Patent 91 04 680, French Patent 2 702 369 and International Patent WO 89/09579. In the International Patent WO 89/09579, which forms the generic state of the art, two transversal supports are integrated into the tibia at a distance from an upper resection surface of the tibia. Two joint surface units are supported, each in one recess in the transversal support via joint surface supports and are secured by means of stud screws. The recesses run axially in the transversal support and the joint surface supports can be inserted into the recesses only from above.
To have an adequate clearance for assembly of the joint surface units with the joint surface supports in the transversal supports, the bone of the upper thigh, i.e., the femur and the tibia, must be spread apart, but that is limited by the cruciate ligaments.
Therefore, with the known endoprostheses system, the anterior cruciate ligament must be resected, although it is a well-known fact that the anterior cruciate ligament is important as a central supporting pillar for the stability of the knee and also to support the physiological movement of the knee.
For implantation of these known knee joint endoprosthesis systems, resection of the anterior cruciate ligament is necessary, although the importance of the anterior cruciate ligament as a central supporting pillar in the stability of the knee as well as in supporting physiological motion of the knee is well-known.
The reasons for the known measures include stability problems with the prostheses developed so far, surgical problems due to the use of the prostheses proximally as well as the limited possibilities of adjusting the prostheses in alignment with the inclination of the tibia plateau.